Solar eclipses and their effects in the ionospheric plasma

0465441 - ÚFA 2017 RIV TW eng A - Abstract
Koucká Knížová, Petra
Solar eclipses and their effects in the ionospheric plasma.
6th IAGA/ICMA/SCOSTEP Vertical Coupling Workshop: Abstracts. Taipei: International Association of Geomagnetism and Aeronomy (IAGA), 2016. s. 32.
[IAGA/ICMA/SCOSTEP Workshop on Vertical Coupling in the Atmosphere-Ionosphere System /6./. 25.07.2016-29.07.2016, Taipei]
R&D Projects: GA ČR(CZ) GA15-24688S
Institutional support: RVO:68378289
Keywords : acoustic-gravity waves * ionosphere * solar eclipse
Subject RIV: DG - Athmosphere Sciences, Meteorology
http://www.ss.ncu.edu.tw/~vcais6/ABSTRACTS%2020160713.pdf

Terrestrial atmosphere shows a high variability over a broad range of periodicities, which mostly consists
of wave-like perturbations characterized by various spatial and temporal scales. The interest for short
time variability in ionospheric attributes is related to the role that ionosphere plays in the Earth's
environment and space weather. Acoustic-gravity waves (AGWs), waves in the period range from subseconds
to several hours, are sources of most of the short-time ionospheric variability and play an
important role in the dynamics and energetics of atmosphere and ionosphere systems.

During solar eclipse, the lunar shadow creates a cool spot in the atmosphere that sweeps at supersonic
speed across the Earth’s atmosphere. The atmosphere strongly responds to the decrease in ionization
flux and heating. The very sharp border between sunlit and eclipsed region, characterized by strong
gradients in temperature and ionization flux, moves throughout the atmosphere and drives it into a nonequilibrium
state. Acoustic-gravity waves contribute to the return to equilibrium. At thermospheric
heights, the reduction in temperature causes a decrease in pressure over the totality footprint to which
the neutral winds respond. Thermal cooling and downward transport of gases lead to neutral composition
changes in the thermosphere that have significant influence on the resulting electron density distribution.
Although the mechanisms are not well understood, experimental studies show direct evidence that solar
eclipses induce wave-like oscillations in the acoustic-gravity wave domain.
Permanent Link: http://hdl.handle.net/11104/0264000